TRANSITION PHRASES - Patent law

Transition phrases are limited in number and have a very distinct function for claim interpretation. Structurally, the transition phrases link the claim preamble with the claim body but they serve more than a simple bridge function; they provide specific guidance as to whether to read the claim limitations as being the minimum elements necessary for the invention (open claim) or whether the claim limitations make up the entire invention (closed transition), or somewhere in-between (partially open).Typical transition phrases include consisting of ,consisting essentially of , comprising,having, including, and containing.
The transition phrase consisting of is a closed transition that indicates that the elements immediate subsequent to the term define the sole elements of the group or subgroup those elements are a part of. Let’s consider the very basic composition claim:

A composition consisting of A and B.

In this claim, the transition consisting of is followed by the elements of A and B, and those two elements form the group that the transition phrase is applied to. Since consisting of is a closed transition phrase, the elements of the subgroup immediately following the transition are the only allowed elements that satisfy the claim and“excludes any element, step, or ingredient not specified in the claim.” However, Gina composition claim, the claim is still open to include impurities typically associated with those materials. Another way to read this claim containing “consisting of A and B” is to read it as saying “consisting of A and B and only A and B” and any impurities typically associated with those two materials.

The meaning of the transition phrase consisting of can be significant both when one is considering whether one is infringing that claim (freedom to operate), or whether the claim reads on prior art (patent ability of the claim). For example, if a prior art composition was described that contained only the material A, then that prior art doe snot describe exactly the claimed composition since the claimed composition requires A and B. Likewise, a prior art composition containing A, B, and C does not describe the exact same thing as the claimed material since the claimed composition requires not only A and B, but only A and B (and not A, B, and C). Similarly, making, using,or selling a composition consisting of A only, or A, B, and C would not infringe the claim since the claim requires A and B and only A and B, assuming, of course, that C is not an impurity typically associated with A and B. Further, C must be related in some way to the claimed invention and cannot simply be an unrelated item included to avoid infringement of a patent.On the other end of the transition phrase spectrum are open transition phrases exemplified most commonly by comprising and less commonly by including, containing,or characterized by. Unlike the closed transition consisting of , the presence of one of these open transitions means that the listed elements of the claim sub sequent to the transition are the minimum elements to satisfy the claim and that additional ingredients, even in very large amounts can be included and the limitations of the claim may still be met. An example of a very basic open claim is:

A composition comprising A and B.

In this claim, the transition comprising is followed by the elements A and B. Since comprisingis an open transition phrase, the elements following the transition are the minimum elements required to satisfy the claim, and the claim must also be read to include any and all additional ingredients even though unstated. Another way to read this claim containing “comprising A and B” is to read it as saying “containing a minimum of A and B.” As we saw in our discussion of the closed phrase consisting of, the reading of comprising affects the way the claim is read when determining whether one is infringing that claim (freedom to operate) or whether the claim read son prior art (patentability of the claim). For example, if a prior art composition was described that contained only the material A, then that prior art does not describe the claimed composition since the claimed composition requires A and B as a minimum.

However, a prior art composition containing A, B, and C would anticipate the claim language since it contains the minimum required elements of A and B. Unlike the potential in fringer who wished to design around the previous claim containing the closed transition consisting of by adding a little bit of the additional element C to the composition of A and B claimed earlier, the potential in fringer would be less successful here, because the open transition means his making, using, or selling the

FIGURE :Claim with open and closed transitions.

composition containing A and B is sufficient to read on the claim, despite the presence of additional ingredient(s) (like C).

In claim language, it is very common to include a plurality of groups that might be connected by different transition phrases. Unlike mathematics where a commonly established order of operations can be applied, claim language rests closer to real language and as a result, the interpretation of relationships between multiple transition phrases is not always straightforward. Nevertheless, let’s briefly consider the claim in Figure above, which uses the phrase comprising and twice uses the phrase consisting of . Is this an open or closed claim?
You may have noticed the preamble a pharmaceutical composition is followed by the transition phrase comprising and so, Aha!, the claim is open and therefore requires only the compound of formula I and at least one pharmaceutically acceptable excipient. This is correct, provided we understand that the compound of formula I has a separate set of definitions that cannot be augmented despite the open transition phrase immediately preceding the compound. In other words, this claimmay contain compounds or ingredients in addition to a compound of formula I but will not be understood to expand on the definitions of formula I itself. For example, Ra and Rbare each closed sets that consists of hydrogen, C1-3 alkyl and halogen, and those groups only. This is likewise true for the definition set of R1 and R2. To make this clearer, the claim drafter has placed the language consisting of immediately before these Markush subsets, meaning that the group immediately following the transition is a closed group. The key point is that when the phrase consisting of appear sin a clause of the body of a claim rather than immediately after the preamble, the consisting of limits only the element set listed in that clause.

This begs the question of what effect the transition comprising has in this example. We have already seen that we cannot read the claim to allow addition to structural formula I itself. However, the preamble to the claim clearly explains that a pharmaceutical composition is being claimed and not merely a compound. We do not need to get into the exact nature of any claim construction limitations that this preamble might introduce to appreciate that this claim is not limited in scope to the compound of formula I and at least one pharmaceutically acceptable excipient, but would also cover the addition of materials that might be understood to go into a pharmaceutical composition. If the preamble is understood to be a limitation of the claim, then the claim can be read to be broad enough to capture the compound in a pharmaceutical composition but not so broad as to capture the compound in any possible setting, to ensure this interpretation, the patent drafter has carefully added an additional required element, the pharmaceutically acceptable excipient.

Sometimes, the claim drafters wish to draft a claim that is intermediate in scope and look to the transition phrase for help in accomplishing this task. Even though claim scope can be modulated by the judicious use of claim limitations (pharmaceutically acceptable excipients) and controlling preamble language (pharmaceutical composition), it is nevertheless sometimes difficult, if not impossible, to envision the scope and effect all the prior art might have or all the ways that prospective users of your claimed invention might find to design around your claims. The use of consisting of may narrow a claim too much, making it harder to enforce against a potential in fringer making, using, or selling your composition but including some additional but yet unimportant ingredients. At the other extreme, the use of comprising may open the claim up too much, possibly broadening it to include elements that together with the explicitly claimed elements could cause the claim to read upon the prior artor to not be properly enabled for such a broad scope, and in either case adversely affecting patentability. Since an inventor cannot specifically account for each and every trace ingredient that a putative in fringer might add to try to avoid infringement of a closed claim, it would be helpful to be able to open up a claim enough to include such inert ingredients without opening the claim to include additional active or otherwise significant ingredients. Conveniently, the closed transition consisting of can be broadened to the term consisting essentially of, which indicates that claim elements from the subgroup following the transition are open to include additional elements that would not “materially affect the basic and novel characteristics” of the

FIGURE :Examples of Markush groups.

claimed invention. This transition phrase effectively allows the patentee to capture the essence of what he believes is his invention without being rigorously tied down to a precise product that can be readily skated around by a clever in fringer, while at the same time not opening the invention up to the extent that it affects the novelty of the claimed composition in view of the prior art. An easy way to remember, if not understand, this transition phrase is that it dictates scope some where between the closed transition of consisting of and the open transition comprising and should be considered where consisting of is too narrow and comprising too broad.